Supplemental Equity and Comprehensive Income Information (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Amount Reclassified from Accumulated Other Comprehensive Income
Selling, general and administrative expenses	$ (1,646)	$ (1,610)	$ (3,278)	$ (3,199)
Total before tax	205	(110)	307	(253)
Tax effect	(537)	(458)	(1,000)	(928)
Net of tax	1,442	1,032	2,721	1,910
Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Net of tax	(63)	(150)	(120)	(281)
Defined Benefit Pension and Postretirement Plans Adjustment
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	92	144	183	287
Defined Benefit Pension and Postretirement Plans Adjustment | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Transition asset	0	0	0	1
Prior service benefit	15	20	30	40
Net actuarial loss	(107)	(164)	(213)	(328)
Total before tax	(92)	(144)	(183)	(287)
Tax effect	32	53	62	111
Net of tax	(60)	(91)	(121)	(176)
Debt and Equity Securities, Unrealized Gain (Loss)
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	1	(6)	3	(6)
Debt and Equity Securities, Unrealized Gain (Loss) | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Selling, general and administrative expenses	0	0	0	0
Total before tax	0	0	0	0
Tax effect	0	0	0	0
Net of tax	0	0	0	0
Cash Flow Hedging Instruments Unrealized Gain (Loss)
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	(16)	12	(13)	50
Cash Flow Hedging Instruments Unrealized Gain (Loss) | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Total before tax	(5)	(91)	1	(164)
Tax effect	2	32	0	59
Net of tax	(3)	(59)	1	(105)
Cash Flow Hedging Instruments Unrealized Gain (Loss) | Foreign currency forward/option contracts | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Cost of sales	(6)	(3)	(2)	(9)
Cash Flow Hedging Instruments Unrealized Gain (Loss) | Foreign currency forward contracts | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Interest expense	0	(89)	0	(155)
Cash Flow Hedging Instruments Unrealized Gain (Loss) | Commodity price swap contracts | Reclassifications out of Accumulated Other Comprehensive Income Attributable to 3M
Amount Reclassified from Accumulated Other Comprehensive Income
Cost of sales	$ 1	$ 1	$ 3	$ 0